Initial corrosion observed on the atomic scale

被引:219
作者
Renner, FU
Stierle, A
Dosch, H
Kolb, DM
Lee, TL
Zegenhagen, J
机构
[1] Max Planck Inst Met Res, D-70569 Stuttgart, Germany
[2] European Synchrotron Radiat Facil, F-38043 Grenoble, France
[3] Univ Ulm, Abt Elektrochem, D-89081 Ulm, Germany
关键词
D O I
10.1038/nature04465
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
Corrosion destroys more than three per cent of the world's GDP(1). Recently, the electrochemical decomposition of metal alloys has been more productively harnessed to produce porous materials with diverse technological potential(2,3). High-resolution insight into structure formation during electrocorrosion is a prerequisite for an atomistic understanding and control of such electrochemical surface processes. Here we report atomic-scale observations of the initial stages of corrosion of a Cu3Au(111) single crystal alloy within a sulphuric acid solution. We monitor, by in situ X-ray diffraction with picometre-scale resolution, the structure and chemical composition of the electrolyte/alloy interface as the material decomposes. We reveal the microscopic structural changes associated with a general passivation phenomenon of which the origin has been hitherto unclear. We observe the formation of a gold-enriched single-crystal layer that is two to three monolayers thick, and has an unexpected inverted (CBA-) stacking sequence. At higher potentials, we find that this protective passivation layer dewets and pure gold islands are formed; such structures form the templates for the growth of nanoporous metals(2). Our experiments are carried out on a model single-crystal system. However, the insights should equally apply within a crystalline grain of an associated polycrystalline electrode fabricated from many other alloys exhibiting a large difference in the standard potential of their constituents(4), such as stainless steel ( see ref. 5 for example) or alloys used for marine applications, such as CuZn or CuAl.
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页码:707 / 710
页数:4
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